<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<script>
			var name = "America";
			var acount = 0;
			var weizhi = name.indexOf("a");
			while(weizhi!=-1){
				weizhi = name.indexOf("a"),weizhi+1;
				acount++
			}
			alert(acount)
		</script>
	</body>
</html>
